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Title: Neutron Lifetime and Axial Coupling Connection

Here, experimental studies of neutron decay, n→pe¯ν, exhibit two anomalies. The first is a 8.6(2.1) s, roughly 4σ difference between the average beam measured neutron lifetime, τ beam n = 888.0(2.0) s, and the more precise average trapped ultracold neutron determination, τ trap n = 879.4(6) s. The second is a 5σ difference between the pre2002 average axial coupling, gA, as measured in neutron decay asymmetries g pre2002 A = 1.2637(21), and the more recent, post2002, average g post2002 A = 1.2755(11), where, following the UCNA Collaboration division, experiments are classified by the date of their most recent result. In this Letter, we correlate those τ n and g A values using a (slightly) updated relation τ n(1+3g 2 A) = 5172.0(1.1) s. Consistency with that relation and better precision suggest τ favored n = 879.4(6) s and g favored A = 1.2755(11) as preferred values for those parameters. Comparisons of g favored A with recent lattice QCD and muonic hydrogen capture results are made. A general constraint on exotic neutron decay branching ratios, <0.27%, is discussed and applied to a recently proposed solution to the neutron lifetime puzzle.
 [1] ;  [2] ;  [3]
  1. Univ. of Alberta, Edmonton, AB (Canada)
  2. Brookhaven National Lab. (BNL), Upton, NY (United States)
  3. New York Univ., New York, NY (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 0031-9007; PRLTAO
Grant/Contract Number:
Published Article
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 120; Journal Issue: 20; Journal ID: ISSN 0031-9007
American Physical Society (APS)
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Country of Publication:
United States
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; neutron; anomalies; decay; asymmetry; coupling; PDG; cosmology; axial; astrophysics; particle physics
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1439292